The Central Coordinating Core (CCC) coordinates clinical research, database management, and strategic-planning across the PPG. The CCC implements the overall prospective longitudinal design of the program project (PPG) across three clinical sites. The goal is to recruit and to follow a sample of 450 subjects: 200 normal controls and 250 subjects with variable degrees of cognitive impairment attributed to subcortical ischemic vascular dementia (SIVD) or Alzheimer disease (AD). For normal controls < 80 years, cognitive/functional status is assessed every 2 years and magnetic resonance imaging (MRI) is repeated every 4 years. For subjects and older controls > 80 years, cognitive /functional status is followed every year, and MRI is repeated every 2 years. The research projects depend upon the CCC for classifying subjects and for ensuring the quality of key cognitive / functional data. Although the Pathology Core ultimately determines the likelihood of CVD, AD, or mixed AD/CVD, the CCC is responsible for obtaining consent and for coordinating the autopsy program. The CCC manages data from all three Cores (Clinical, Imaging, and Pathology). Key clinical variables include demographics, onset and duration of dementia, activities of daily living, mental status scores, neuropsychological test scores, clinical dementia rating (CDR), clinical diagnosis, and subject categorization. Key imaging data include the number, location, and size of lacunes, the volume of cortical gray matter, white matter, white matter hyperintensities (WML), ventricular and sulcal cerebral spinal fluid, and the volume of the hippocampi. The key pathological data include the overall likelihood ofAD, SIVD, or mixed AD/SIVD, numbers, size, and location of lacunar infarcts, and the severity of neurofibrillary tangles, neuritic plaques, white matter demyelination, and microvascular disease. These data are utilized by all four of the research projects. PPG investigators work well together. In person meetings are held at least twice a year to review progress, set goals, and to plan strategy. Monthly teleconferences are conducted to check progress and maintain course. Electronic communication tools, especially e-mail, mitigate the geographic distances between campuses. Consultants and an external advisory group provide invaluable feedback and guidance. The PPG functions as a vital and cohesive whole.